The objective of this research is to characterize early biochemical events involved in the development of degenerative changes in the articular cartilage of dogs that have a high incidence of spontaneous osteoarthritis associated with malarticulation of the femoral head -i.e., hip dysplasia. A systematic analysis would be made of synthetic and degradative products of collagen in the articular cartilage of normal and diseased joints. Prominence would be given to analysis of a recently described defect of collagen metabolism (increase in procollagen) in the degenerative articular cartilage of young dogs, because these changes have predictive value and might have a meaningful relationship to the development and/or progression of disease. The object is to pinpoint the focal abnormality in cartilage metabolism in relation to the onset and progression of disease. Correlations would be drawn with changes in the joint revealed by radiographic analysis and histological and histochemical changes in other joint tissues, i.e., capsule, ligament, synovial membrane, and synovial fluid. An effort would be made to identify and characterize specific defects of cartilage collagen metabolism using both cell culture and tissue explant techniques. The ultimate goal is to elucidate the pathogenic processes associated with the development of structural defects in the articular cartilage, and to relate these changes to the natural history of osteoarthritis.